<SEC-DOCUMENT>0001140361-15-011590.txt : 20150312
<SEC-HEADER>0001140361-15-011590.hdr.sgml : 20150312
<ACCEPTANCE-DATETIME>20150312193246
ACCESSION NUMBER:		0001140361-15-011590
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150302
FILED AS OF DATE:		20150312
DATE AS OF CHANGE:		20150312

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARDELYX, INC.
		CENTRAL INDEX KEY:			0001437402
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		34175 ARDENWOOD BLVD.
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94555
		BUSINESS PHONE:		510-745-7047

	MAIL ADDRESS:	
		STREET 1:		34175 ARDENWOOD BLVD.
		CITY:			FREMONT
		STATE:			CA
		ZIP:			94555

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NTERYX INC
		DATE OF NAME CHANGE:	20080611

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			JUE GEORGE
		CENTRAL INDEX KEY:			0001203449

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-36485
		FILM NUMBER:		15697292

	MAIL ADDRESS:	
		STREET 1:		749 N MARY AVENUE
		CITY:			SUNNYVALE
		STATE:			CA
		ZIP:			94085
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4/A
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2015-03-02</periodOfReport>

    <dateOfOriginalSubmission>2015-03-04</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001437402</issuerCik>
        <issuerName>ARDELYX, INC.</issuerName>
        <issuerTradingSymbol>ARDX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001203449</rptOwnerCik>
            <rptOwnerName>JUE GEORGE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ARDELYX, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>34175 ARDENWOOD BLVD, SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>FREMONT</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94555</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Operations</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4220</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This amendment is filed solely to correct the number of shares held indirectly by the reporting person.  The updated total reflects the acquisition of 165 shares under the Issuer's Employee Stock Purchase Plan.</footnote>
        <footnote id="F2">The shares are directly held by the Reporting Person's daughter.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Elizabeth Grammer, Attorney-in-Fact for George Jue</signatureName>
        <signatureDate>2015-03-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
